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Cytogenetic Effects of Conventional and Ultra High Dose Rates of Radiation in Human Lymphocytes: Comparative Analysis in Metaphase Chromosomes and G2-PCCs

Published online by Cambridge University Press:  12 December 2025

Maria B. Escalona ,
Terri L. Ryan ,
Samantha R. Gross ,
Carol J. Iddins Open the ORCID record for Carol J. Iddins [Opens in a new window] ,
Helen C. Turner  and
Adayabalam S. Balajee
Maria B. Escalona
Affiliation:
Cytogenetic Biodosimetry Laboratory, Radiation Emergency Assistance Center/Training Site, Oak Ridge Institute for Science and Education , Oak Ridge Associated Universities, Oak Ridge, TN, USA
Terri L. Ryan
Affiliation:
Cytogenetic Biodosimetry Laboratory, Radiation Emergency Assistance Center/Training Site, Oak Ridge Institute for Science and Education , Oak Ridge Associated Universities, Oak Ridge, TN, USA
Samantha R. Gross
Affiliation:
University of Tennessee Knoxville , Knoxville, TN, USA
Carol J. Iddins
Affiliation:
Cytogenetic Biodosimetry Laboratory, Radiation Emergency Assistance Center/Training Site, Oak Ridge Institute for Science and Education , Oak Ridge Associated Universities, Oak Ridge, TN, USA
Helen C. Turner
Affiliation:
Center for Radiological Research, College of Physicians and Surgeons, Columbia University Irving Medical Center , New York, NY, USA
Adayabalam S. Balajee*
Affiliation:
Cytogenetic Biodosimetry Laboratory, Radiation Emergency Assistance Center/Training Site, Oak Ridge Institute for Science and Education , Oak Ridge Associated Universities, Oak Ridge, TN, USA
*
Corresponding author: Adayabalam S. Balajee; Email: Adayabalam.balajee@orau.org
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Abstract

Objectives

Ultra-high dose rate (UHDR) radiation, popularly known as FLASH, has been demonstrated to selectively kill tumor cells with minimal or negligible effects on normal cells but the biological effects induced by UHDR are not fully understood.

Methods

In this study, cytogenetic damage induced by UHDR radiation was compared with conventional dose rate (CDR) in human peripheral blood lymphocytes. Human blood samples were irradiated with 3 Gy and 8 Gy doses using 9 MeV electrons at 2 different dose rates: CDR 1 Gy/min and UHDR 600 Gy/Sec. Unstable and stable chromosomal aberrations were detected by fluorescence in situ hybridization (FISH).

Results

Reduced yields of chromosomal aberrations were observed after UHDR radiation at both radiation doses and the extent of reduction was more in colcemid arrested metaphase chromosomes than in G2-PCCs.

Conclusions

The reduced yields of chromosomal aberrations detected after UHDR of electrons may be due to rapid delivery of radiation dose within seconds, resulting in a non-uniform exposure of lymphocytes with varying levels of DNA damage induction. Future studies using well defined human equivalent in vivo and in vitro model systems are required to determine the underlying mechanisms for the FLASH effects.

Keywords

ultra-high dose rate radiationhuman lymphocyteschromosomal aberrationsmetaphase chromosomescalyculin A induced prematurely condensed chromosomesfluorescence in situ hybridization

Information

Type
Original Research
Information
Disaster Medicine and Public Health Preparedness , Volume 19 , 2025 , e350
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of Society for Disaster Medicine and Public Health, Inc

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